Safety switch for electric irons



Dec. 15,1925. 1,565,499

T. A.REID` A vSAFE'I'Y SWITCH FOR ELECTRIC IRONS Filed Dec. '7, 1921 13 1l 11 Il 1 11 WITNESSESZ INVENTOR V MA- im Patented Dec.; 15, 1925.

UNITED STATES PATENT OFFICE,

THOMAS A. REID, F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 8c MANFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

SAFETY SWITCH FOR ELECTRIC IRONS.

Application filed December 7, 1921. .Serial No.V 520,605.

To all lwhom t may concern:

Be it known that I, THOMAS A. REID, a citizen of the United States, and a resident ofVVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement inv Safety Switches for Electric Irons, of which the following is a specification.

My invention relates to electrically heated apparatus and particularly to electrically heated flat irons, and it has for its object to provide a relatively simple, inexpensive, and easily manufacturedtemperature-limiting device for an electrically heated ,-at iron.

It is highly desirable to provide an electrically heated fiat iron with means for in` terrupting the circuit through the heating element of the iron in case the iron is left unattended with Y current traversing the heating element, in order to prevent undue rise of temperature and thc resultantpossibility of causing a lire.

My invention embodies a closed tubular member of substantially spiral form secured to the body portion of the iron and operating as a locking means for a manually closable switch also mounted on the body portion of the iron. The tubular member is filled with a material which fuses at a predetermined temperature, causing a movement of the free end of the tubular member whereby the switch is released and moved to its open position by a spring member. The switch is manually closable from the outside of the iron, the handle of the switch serving .to indicate whether the switchl is in its open or in its closed position.

In the single sheet of drawings,

lFigure 1 isla view, in side elevation, of an electrically heated iron comprising the delvice embodying my lnventlon, certain portions being cut away and others being shown in longitudinal section;

Fig. 2 is a top plan view of an electric iron, portions being cut away to` show the switch mechanism.

An electric iron comprises a bottom plate 10, an electric heating element lland a top plate 12, the 'three members constituting what may be termed the body portion of the iron. A cover member 13'is held in opera- 'tive engagement with the body portion of,-

substantially Lshape and are provided, at

their upper ends, with contact-terminal studs 22 suitably secured thereagainst. The studs 22 project through a suitable opening at the rear. of the cover member 13, an inf sulating member 23 being provided to maintain the studs 22 and the terminal straps 19 in proper operative positions relatjively to each other and to the cover mem- A switch mechanism for'clos'ing and for interrupting the circuit through the resistor of the heating element comprises a rod 24 extending longitudinally of the 4iron and moving .in an opening 25 in a Ilug 26 provid- -ed on, or secured to, the vtop member. 12

ynear the rear end thereof. yA push rod I 27 .is securely mounted, lon the outer. endof the rod 24 and extends through an opening 28 in the rear ofthe cover member to permit of the operator pressing tliereagainst to close the fsw'itcl'i. A coil spring 29 is-locatedon the rod 24 be-v tween the upstanding lug 26 and' the-push I rod 27 and is effective-to resiliently bias the switch to its open position with a greater portion of the length of the lpush rod 27 projecting through the 'opening 28. The

tionary contact member 31 whichis mounted on, but insulated' from, the top plate, by -means of a bolt 32,` and a relatively movable contact 33yvhich is mountedl on the rod 24. The inner end of` the` rod 24 `is provided with a hook 34 for a purpose to be hereinafter set forth in detail.

'A locking means, under the thermal control of the iron, comprises aclosed tube 35 switch proper comprises a substantially staof substantially spiral form, the end of l which isy secured against the top plate 12 by meansof a bolt 36. The tube 35 is filled with a suitable material 37 such as lead or antimony, lead alloy, or fusible salts, such 'as potassium chlorate, and by its subsequent expansion causes the tube to artly uncoil. The free end of the tube is ormed into a hook 38 which is located in the path of travel of the hook 34.- on the rod of lthe switch as long as the temperature of the body portion of the iron is below a pre-4 determined value. In case the temperature yofthe body p ortion` of theiron exceeds a predetermined value the material within the tube fuses and expands, thereby causing the hook 38 of the coil to move away from -the hook 34 of the switch rod, thus permitting the coil 'spring 29 'to quickly interrupt' a the circuit through the heating element of theA iron.

The mechanism is effective to permit the operator to close the switch but is ineffective to retain the switch in its closed position when the temperature exceeds said predetermined value, and the temperature must drop materially below the predetermined Avalue before the mechanism is again effec- 'tive to lock the switch in its closed position. The tube hereinbefore described as constiwhether the switch in its open or its portion.

closed position.A

I claim as my-inventionzl. A temperature-limiting' means for an electrically heated device 4comprising a switch mounted on the body portion of said heated device, means manually actuated from-the outside of a covery member of said heated device for moving said switch to its closed position, and thermally' controlled -means, comprising a closed tube filled with a :fusible material and having one end rigidly mounted on the body portion of said heated device, for'holding said switch in its closed position and' forpermitting said switch to open upon the occurrence of a predetermined tempeature .in the body 2. A temperature-limiting means for an electrically -heated device comprising a switch mounted on the body .portion of said heated device and spring-biased to its open A position, means manually actuated from the outside of a cover member of said heated device for moving said switch to its closed position, a sealed tubular member, of spiral-coil form, for normally holding said switch in its closed position, and material in said tube 'fusible at ka predetermined temperature and effective thereby to cause a turning movement of said tubeto release said switch.4

3. A .temperature-limiting means for an electrically heated -device comprising a switch Imounted on a bod portion of said heated deviceand springia'sed toits open position, means manually actuated from the outside of a cover of said heated device for moving said switch' to its closed position, a sealed tubular member, of spiral-coil form, having one end rigidly secured to the body portion and having its entire length in heat-receiving relation thereto, for normally holding saidswitch. in its closed position, and means in said tubular member that fuses at a predetermined temperature and causes a turning movement of said tubular member whereby said switch is released.

4. A temperature-limiting means for an electrically -heatcd 'device comprising a switch mounted on a body portion of' said 'heated device, vresilient means for biasing said switch to its open position, means A manually actuated from the outside of a cover member of said device for moving'- said switch to its closed position, and resilient means mounted on the body portion for normali holding said switch in its closed position, said means comprising a sealed tube of spiral form, and a material in said tube fusible ata predetermined temperature and operative thereby to cause said tube to release said switch.

5. A temperature limiting means for an electrically, heated devicel comprising a Vswitch springsbiased to its open position,

means manuall-y 'actuated from the outside of acover member of the heated device for moving saidswitch to its closed position, and ymeans comprising a sealed tube and a fusible material therein, under the thermal control of the body portion of said device.

-for'normally locking said 'switch in its closed position and -for permitting said switch to open upon the '.occurrence of a predetermined temperature in the body port-ion.

In testimony whereof, I have hereunto subscribed my name` this 25th day of November, 1921. f

' THoiuAsA. REID. 

